Intel has announced the Extensible Host Controller Interface (xHCI) draft specification, revision 0.9, is now available for review, making USB 3.0 one step closer to reality. The news comes just ahead of the Intel Developer Forum (IDF) in San Francisco next week.

The USB 3.0 architecture was first demonstrated at last year's IDF show and is on track for finalization this year, with products hitting the market in 2009. The chief improvement in USB 3.0 will be a ten-fold increase in throughput to 4.8 gigabits per second, or 600 megabytes per second.

At that speed, USB 3.0, also known as "SuperSpeed USB," would be faster than the Serial ATA (SATA) controllers used on today's hard drives. This could have a major impact on the market, notes Gartner analyst Steve Kleynhans, who noted that USB 2.0 was fast enough to bring about cheap, mass market external storage.

"USB 2.0 allowed external storage of all types," he told InternetNews.com. "Before then, if you wanted an external optical drive, you had to use a proprietary or SCSI connector, and that wasn't cheap."

USB 2.0 led to the ability to use digital cameras and camcorders, since before there wasn't a way to connect the digital device to the PC before to get pictures and video off, at least with any great speed. So who knows what 3.0 will allow, said Kleynhans.

"Whenever you bump up performance by such a great level, you open up the opportunities for apps people haven't thought of yet," he said. "Don't forget, this is faster than Ethernet. So all of a sudden, USB 3 becomes a very viable way to connect external drives that will be as fast if not faster than an internal."

Kleynhans said the speedy USB 3.0 port would not be a threat to SATA but could render IEEE 1394, a.k.a. FireWire, obsolete. That spec is trying to keep up the race, with a new specification, IEEE 1394-2008, released earlier this month that offers 3.2 Gb/sec of throughput.

Intel's xHCI is something of vital interest to component designers, because it describes the hardware/software interface between system software and the host controller hardware for USB 3.0 and USB 2.0. This saves third parties from having to make their own controller, they can just use Intel's which is available royalty-free.

Intel (NASDAQ: INTC) will have a USB 3.0 Technical session and a USB 3.0 Promoter Group area in the USB community booth where a technology demo will be shown, according to an Intel spokesperson.

A new form of power draw

In addition to the speed boost, USB 3.0 will feature a new form of power draw that will be much more merciful on laptops and battery-powered devices. USB 2.0, the current spec, is what's called poll-driven. When a USB device is plugged into a port, the computer keeps polling the port, which is a drain on batteries.

On a desktop, this isn't really an issue, but on a notebook, it's noticeable, said Kleynhans. "Some notebooks weren't living up to battery life, and the only difference was one had a Webcam, which turned out to be a USB device internally that caused the USB ports to stay active and thus drain the battery," he said.

USB 3.0 will be interrupt-driven, so if nothing is happening with the device, the machine doesn't poll it and therefore, the CPU can power down into a low power state and thus preserve battery life.

The advent of USB 3.0 doesn't mean 2.0, or even 1.1 will go away. Many devices simply don't need the speed of a 2.0 or 3.0 and 1.1 will do just fine. Just as modems got faster but still could connect at slower speeds, PCs will always maintain backwards compatibility even as USB 3.0 products hit the market.